Abstract: Experimental investigation on the unsteady flow in the vaned diffuser of a centrifugal compressor stage was performed. Detailed instantaneous flow has been measured at several different measuring positions using a hot-wire anemometer with the phase-locked ensemble-averaged technique. Different unsteady source are distinguished by circumferential-averaged technique and ‘inverse spectral analysis’. The effects of different unsteady source on the flowfield and mechanism of the unsteady interaction are analyzed and explored. The results show that the repercussion effect of vaned diffuser is of the same order with the unsteadiness induced by impeller, while the repercussion effect of vaned diffuser is smaller. The repercussion effect of vaned diffuser and the unsteadiness induced by impeller decrease along the stream wise direction, and the gap between them also reduces along this direction. The unsteady effect of impeller is sensitive to the location of diffuser vane in radial gap, and it is larger near the convexity surface of the diffuser vane. The uncertain unsteady dimensionless velocity in radial gap is influenced by the repercussion effect of vaned diffuser insignificantly.

Key words: Repercussion effect of vaned diffuser; Impeller wake; Inverse spectral analysis; Unsteady source; Vane position

摘要： 使用热线风速仪对扩压器内的非定常流场进行了测量,采用锁相采样—集平均技术对热膜测量的瞬时信号进行了处理,对离心压气机内扩压器势反冲效应和叶轮尾流的非定常影响进行了分离,采用“逆频谱分析”方法求解了不确定性非定常性,研究了离心压气机内不同非定常源的影响。结果表明,扩压器的势反冲效应同叶轮叶片的非定常影响处于同一数量级,扩压器的势反冲效应略小一些。扩压器的势反冲效应同叶轮叶片的非定常影响均是沿流向不断减小,且二者之间的差距沿流向也不断减小。叶轮叶片的非定常影响对扩压器叶片的位置较为敏感,靠近扩压器凸面侧的测点受叶轮叶片的非定常影响较大。径向间隙内不确定非定常度受扩压器叶片的反冲影响较大。

关键词: 扩压器势反冲效应;叶轮尾流;逆频谱分析;非定常源; 叶片位置